Monday, December 5, 2016

Puget Sound Snow Threat is Done, But More Exciting Weather is Yet to Come

Our minor lowland snow event is nearly over, with only some wet snow near sea level and modest snow above 500-700 ft. As noted in my previous blog, the problem was temperature: too warm at low levels. But plenty of snow in the mountains.

The only real snow during the next few hours will be around Port Angeles and the NE Olympics, where Fraser Valley flow will be forced to rise (see forecast for 3-h snow ending 4 AM).

But there is a lot of weather fun that will occur over the next few days over the Northwest, including:

The coldest low temperatures over the western lowlands since last January (down to the mid-20s!)

So we were supposed to get 2"-4" in the convergence last night. I'm disappointed. It was cold enough- 29 degrees this AM- but the moisture supply failed.

Honestly, the only way we get snow to last is when the snow falls as cold snap moves in and meets the moisture. When the moisture pushes out the cold air, the snow only lasts a few hours before the rain...

I echo John K's request for information about the Fraser River flow and how it impacts us. Thanks!

On a side note, it would be nice to have an easier way to prove I am not a robot. I had to click through 11 screens (I counted) to be verified. To just enter a few letters or numbers would be so much nicer.

John K, much like the Columbia River Valley the Fraser River Valley is a gap in the mountains that allows cold air to seep or stream out of the interior where the pressure is higher and the air is colder. Thus the outflow winds often keeps areas near the ends of the valleys cooler and leads to snow and freezing rain events when other areas are already seeing rain. If there is enough cold air and pressure these winds can extend much further, well into Washington.

Those easterly Columbia River Gorge winds are harsh. I used to have to spend quite a bit of time east of Portland, just outside the Gorge. Even outside the mouth of the Gorge, they were quite piercing, and sometimes they can persist for weeks.

I'll take my current locale with ample but mild convergence zone rain over those winds any day.

Fortunately, you didn't usually have to get far off the river to find shelter from them given the hilly terrain around Portland.

Thanks Dr. Mass,My question evolves around professional intuition and trusting the models. In an episode of Doogie Howser he was challenged to go beyond the models and trust his instinct. Being a dedicated professional in the realm of pnw meteorology, how much leeway do you feel you have to use professional judgement as opposed to just reciting and reading model ensembles?